131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
/* aes.c */
|
|
/*
|
|
This file is part of the ARM-Crypto-Lib.
|
|
Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <stdint.h>
|
|
#include <string.h>
|
|
#include "gf256mul.h"
|
|
#include "aes.h"
|
|
#include "aes_invsbox.h"
|
|
#include "aes_dec.h"
|
|
|
|
void aes_invshiftrow(void* data, uint8_t shift){
|
|
uint8_t tmp[4];
|
|
tmp[0] = ((uint8_t*)data)[(4+0-shift)&3];
|
|
tmp[1] = ((uint8_t*)data)[(4+1-shift)&3];
|
|
tmp[2] = ((uint8_t*)data)[(4+2-shift)&3];
|
|
tmp[3] = ((uint8_t*)data)[(4+3-shift)&3];
|
|
memcpy(data, tmp, 4);
|
|
}
|
|
|
|
void aes_invshiftcol(void* data, uint8_t shift){
|
|
uint8_t tmp[4];
|
|
tmp[0] = ((uint8_t*)data)[ 0];
|
|
tmp[1] = ((uint8_t*)data)[ 4];
|
|
tmp[2] = ((uint8_t*)data)[ 8];
|
|
tmp[3] = ((uint8_t*)data)[12];
|
|
((uint8_t*)data)[ 0] = tmp[(4-shift+0)&3];
|
|
((uint8_t*)data)[ 4] = tmp[(4-shift+1)&3];
|
|
((uint8_t*)data)[ 8] = tmp[(4-shift+2)&3];
|
|
((uint8_t*)data)[12] = tmp[(4-shift+3)&3];
|
|
}
|
|
static
|
|
void aes_dec_round(aes_cipher_state_t* state, const aes_roundkey_t* k){
|
|
uint8_t tmp[16];
|
|
uint8_t i;
|
|
uint8_t t,u,v,w;
|
|
/* keyAdd */
|
|
for(i=0; i<16; ++i){
|
|
tmp[i] = state->s[i] ^ k->ks[i];
|
|
}
|
|
/* mixColums */
|
|
for(i=0; i<4; ++i){
|
|
t = tmp[4*i+3] ^ tmp[4*i+2];
|
|
u = tmp[4*i+1] ^ tmp[4*i+0];
|
|
v = t ^ u;
|
|
v = gf256mul(0x09, v, 0x1b);
|
|
w = v ^ gf256mul(0x04, tmp[4*i+2] ^ tmp[4*i+0], 0x1b);
|
|
v = v ^ gf256mul(0x04, tmp[4*i+3] ^ tmp[4*i+1], 0x1b);
|
|
state->s[4*i+3] = tmp[4*i+3] ^ v ^ gf256mul(0x02, tmp[4*i+0] ^ tmp[4*i+3], 0x1b);
|
|
state->s[4*i+2] = tmp[4*i+2] ^ w ^ gf256mul(0x02, t, 0x1b);
|
|
state->s[4*i+1] = tmp[4*i+1] ^ v ^ gf256mul(0x02, tmp[4*i+2] ^ tmp[4*i+1], 0x1b);
|
|
state->s[4*i+0] = tmp[4*i+0] ^ w ^ gf256mul(0x02, u, 0x1b);
|
|
|
|
/*
|
|
state->s[4*i+0] =
|
|
gf256mul(0xe, tmp[4*i+0], 0x1b)
|
|
^ gf256mul(0xb, tmp[4*i+1], 0x1b)
|
|
^ gf256mul(0xd, tmp[4*i+2], 0x1b)
|
|
^ gf256mul(0x9, tmp[4*i+3], 0x1b);
|
|
state->s[4*i+1] =
|
|
gf256mul(0x9, tmp[4*i+0], 0x1b)
|
|
^ gf256mul(0xe, tmp[4*i+1], 0x1b)
|
|
^ gf256mul(0xb, tmp[4*i+2], 0x1b)
|
|
^ gf256mul(0xd, tmp[4*i+3], 0x1b);
|
|
state->s[4*i+2] =
|
|
gf256mul(0xd, tmp[4*i+0], 0x1b)
|
|
^ gf256mul(0x9, tmp[4*i+1], 0x1b)
|
|
^ gf256mul(0xe, tmp[4*i+2], 0x1b)
|
|
^ gf256mul(0xb, tmp[4*i+3], 0x1b);
|
|
state->s[4*i+3] =
|
|
gf256mul(0xb, tmp[4*i+0], 0x1b)
|
|
^ gf256mul(0xd, tmp[4*i+1], 0x1b)
|
|
^ gf256mul(0x9, tmp[4*i+2], 0x1b)
|
|
^ gf256mul(0xe, tmp[4*i+3], 0x1b);
|
|
*/
|
|
}
|
|
/* shiftRows */
|
|
aes_invshiftcol(state->s+1, 1);
|
|
aes_invshiftcol(state->s+2, 2);
|
|
aes_invshiftcol(state->s+3, 3);
|
|
/* subBytes */
|
|
for(i=0; i<16; ++i){
|
|
state->s[i] = aes_invsbox[state->s[i]];
|
|
}
|
|
}
|
|
|
|
|
|
static
|
|
void aes_dec_firstround(aes_cipher_state_t* state, const aes_roundkey_t* k){
|
|
uint8_t i;
|
|
/* keyAdd */
|
|
for(i=0; i<16; ++i){
|
|
state->s[i] ^= k->ks[i];
|
|
}
|
|
/* shiftRows */
|
|
aes_invshiftcol(state->s+1, 1);
|
|
aes_invshiftcol(state->s+2, 2);
|
|
aes_invshiftcol(state->s+3, 3);
|
|
/* subBytes */
|
|
for(i=0; i<16; ++i){
|
|
state->s[i] = aes_invsbox[state->s[i]];
|
|
}
|
|
}
|
|
|
|
void aes_decrypt_core(aes_cipher_state_t* state, const aes_genctx_t* ks, uint8_t rounds){
|
|
uint8_t i;
|
|
aes_dec_firstround(state, &(ks->key[i=rounds]));
|
|
for(;rounds>1;--rounds){
|
|
--i;
|
|
aes_dec_round(state, &(ks->key[i]));
|
|
}
|
|
for(i=0; i<16; ++i){
|
|
state->s[i] ^= ks->key[0].ks[i];
|
|
}
|
|
}
|